How are coupling constants calculated from Maxwell's equations and general relativity?

[Schreiberdk]

Hi there PF

How does on calculate the field strenght of the electromagnetic field (from Maxwells equations) and of the gravitational field (from general relativity).

I want to relate this to particle physics, where the relative strenghts of the fundamental interactions are calculated here (http://en.wikipedia.org/wiki/Fundamental_interaction#Overview), but how are these relative strengths calculated? Does it have something to do with coupling constants? and how does one find these in general relativity and in maxwells equations?

Also i would like to ask, whether these are energy dependent, as in grand unified theories, where on states that the fundamental forces become equal in strenght at certain levels of energy.

Thanks in advance
\Schreiber

 

[Schreiberdk]

Anyone? :)

 

[WannabeNewton]

In Classical GR there is no "field" strength per say since it is space - time geometry and its curvature one is modeling mathematically. One can calculate tensor quantities such as the Riemann Tensor or the Ricci Tensor for a given metric to see how much space - time is curved at each point in the coordinate system being used for the metric or the Ricci Scalar for a coordinate invariant expression for the curvature. Correct if I am wrong.

 

[Schreiberdk]

Can't one then say, that the Ricci Scalar is the coupling constant (i.e. the strenght of gravity) of gravity?

And does this correspond to the relative strenghts of the forces in the link http://en.wikipedia.org/wiki/Fundamental_interaction#Overview ?

And what about electromagnetism ? :)